This book is ideal for those who wish to start learning about the intriguing modem concepts of astrophysics; the birth and evolution of the universe, its large-scale structure, galaxies and their clusters, and stars. The book provides just enough text to give a feeling of what it is all about, such as the non* Euclidean geometry of the universe, while the main point is to cover all the recent major discoveries and novel hy potheses and theories in astrophysics, from quasars and relict radiation to black holes and the neutrino rest mass, the latter having a profound impact on the entire philosophy of the universe. The Russian edition of this book ran into 100,000 copies and is sold out.
Stars are distributed very sparsely within galaxies. In a model in which stars are represented by pinheads, these would be 50 km apart, and the solar system would be a 20-metre circle centred on a pinhead sun. A typical galaxy contains 10u stars, has a radius of 3 x 104 light years, and is 3 x 106 light years from its nearest neighbour. Like a dime, it has a width only about a tenth of its radius, and dimes, spaced about a metre apart, make a good model of the galactic distribution. On this scale, dimes
1.5 km away would represent the farthest visible galaxies, and objects 6 km away would represent the farthest known quasars. However, relatively few galaxies are single. Most belong to clusters of from 2 to 1000, to even 10,000, apparently bound